biostudies-literatureUnknown21(1)Medina Caro D<h4>Background</h4>The Barrancas Blancas (BB) plain, situated in the high-altitude Atacama region, is a cryogenic, hyper-arid, poly-extreme environment. The seasonal formation of a temporary freshwater lake under these harsh conditions provides a unique opportunity to examine how liquid water influences the metabolic responses of desert microbial communities. Using a metatranscriptomic approach, we characterised microbial community responses along a 70-meter natural moisture gradient.<h4>Results</h4>Along the gradient, the most active sites (8-23 m from the lake) exhibited high RNA recovery and diverse metabolic functions. Bacillariophyta (diatoms) drove oxygenic phototrophy, while Pseudomonadota contributed to anoxygenic phototrophy and nitrogen fixation. Additionally, Pseudomonadota, ActEnvironmental microbiome20https://www.ebi.ac.uk/biostudies/studies/S-EPMC12849286biostudies-literatureMetabolic transitions along a moisture gradient in a poly-extreme high-altitude desert ecosystem within the Atacama Desert.PMC12849286Wagner DOses RGarcia AMedina Caro DBartholomaus ALiebner SfalseMetabolic transitions along a moisture gradient in a poly-extreme high-altitude desert ecosystem within the Atacama Desert.<h4>Background</h4>The Barrancas Blancas (BB) plain, situated in the high-altitude Atacama region, is a cryogenic, hyper-arid, poly-extreme environment. The seasonal formation of a temporary freshwater lake under these harsh conditions provides a unique opportunity to examine how liquid water influences the metabolic responses of desert microbial communities. Using a metatranscriptomic approach, we characterised microbial community responses along a 70-meter natural moisture gradient.<h4>Results</h4>Along the gradient, the most active sites (8-23 m from the lake) exhibited high RNA recovery and diverse metabolic functions. Bacillariophyta (diatoms) drove oxygenic phototrophy, while Pseudomonadota contributed to anoxygenic phototrophy and nitrogen fixation. Additionally, Pseudomonadota, Act2026-01-01T00:00:00Z2026 Jan2026-06-10T09:05:24.834Z2026-06-10T03:11:34.042ZS-EPMC128492864157835710.1186/s40793-025-00847-7